Lenses, films, and optical elements for lighting fixtures and other optical systems and components typically provide one or more of the following functions: protection of the light source or other components in the system from external objects such as dust, moisture, accidental contact, etc.; redirection of light such as collimating, converging, diverging and angular or spatial light re-distribution; provide structural rigidity or support for one or more optical components or the system; improve spatial luminance or color uniformity; improve aesthetic appearance; provide other optical effects including absorbing, fluorescing, phosphorescing, filtering, reflecting, de-pixelization, angular or spatial separation or re-distribution of light of one or more wavelength or polarization states; speckle contrast reduction; convey or illustrate information; illuminate a component, system or environment; internal, external or ambient light absorption or re-direction; contrast enhancement; thermal conduction or insulation from the environment or one or more parts of the system; and other modifications of the properties of the electromagnetic waves emitted from the component or system. In addition, other desirable properties related to the component include low cost of manufacture, low cost to install or assemble with high yields, easy to handle, clean, install, or repair.
Typically one or more of the desired or preferred functionalities described above can not be achieved by a single process of casting, extruding, or molding operation. For example, in order to achieve one form of anisotropic diffuser or polarization sensitive optical composite or scattering element, a film is oriented or stretched along one or two axes. These processing requirements typically prohibit the film being greater than approximately 200 μm in thickness due to the typical extrusion equipment and process limitations related to achieving the asymmetry. In some applications an optical component is desired to have specific mechanical, environment, or other optical property that can not be readily achieved with a 200 μm film. These are typical produced in sheet extrusion process in which performing processes such as stretching or orientation is difficult or prohibited.